An analytical tool for understanding the properties and behaviour of variable charge soils

Soil Research ◽  
2007 ◽  
Vol 45 (2) ◽  
pp. 83 ◽  
Author(s):  
G. P. Gillman
Keyword(s):  
Surface Charge ◽  
Large Scale ◽  
Graphical Representation ◽  
Resource Assessment ◽  
Ideal Condition ◽  
Soil Resource ◽  
Variable Charge ◽  
Ph Range ◽  
Soil Resource Assessment ◽  
Insight Into

Routine analyses for soil cation exchange properties usually give only limited insight into the properties and management of soils containing significant amounts of variable charge. In this paper a procedure for determining a soil Charge Fingerprint is fully described, a model developed from simplified theory to underpin the methodology is discussed, and examples of the usefulness of the approach are given. Operationally defined cation and anion exchange capacities (CEC and AEC) are determined over an appropriate pH range (pH 4 to pH 6 is suggested) using Ca and Cl as the index cations. At low pH, Ca does not always fully saturate the CEC, so that it is necessary to distinguish a Basic CEC (Ca ads.) from the Total CEC (Ca + Al ads.). The graphical representation of CECT, CECB, and AEC v. pH constitutes the Charge Fingerprint. Though not intended as a routine instrument, its determination on key samples in a characterisation exercise places routinely determined basic and acidic cations in context. Examples are given of large scale characterisation studies that link soils from different continents having similar surface charge characteristics; of the assessment of the success or otherwise of producing permanent positive charge in synthetically prepared Ti-substituted goethites; and of the evaluation of the effect of adding crushed basic rock amendment on the surface charge properties of a variable charge soil. The formulation of a Depreciation Index, which classifies soils in terms of their departure in basic cation content from an arbitrarily defined ‘ideal’ condition, is suggested for use in soil resource assessment.

Measurement and modeling of surface charge and cation binding in agricultural soil

2008 ◽  
Vol 88 (5) ◽  
pp. 749-759 ◽  
Author(s):  
K M Taillon ◽  
W H Hendershot
Keyword(s):  
Surface Charge ◽  
Agricultural Soil ◽  
Agricultural Soils ◽  
Cation Binding ◽  
Adsorption Behavior ◽  
Adsorption Parameters ◽  
Metal Concentrations ◽  
Variable Charge ◽  
Total Metal ◽  
Ph Range

Models of metal adsorption have typically been developed and tested for soil components rather than whole soils and at cation concentrations higher than usual environmental conditions. This study investigates whether the non-ideal consistent competitive adsorption (NICA) model can be applied to ion binding in whole soils at low total metal concentrations. Surface charge was measured for 18 agricultural soils from southern Quebec over the pH range 3.5 to 8. The adsorption of Ca, Cd, Cu, Pb and Zn was also measured for three total metal concentrations of 2, 5 and 10 mg L-1 at pH 6 in a 0.005 M Ca(ClO4)2 solution. NICA model parameters were solved for each soil using the surface charge and adsorption data and a non-linear least squares fitting routine. Two types of binding sites were identified: the first type had a pKa near 4 while the second type had a pKa near 7.5. The first type of binding site contributed the greater proportion of the variable charge over most of the pH range, and the second site was unimportant at the lower pHs. The surface charge was accurately described by the NICA model with a mean R2 of 0.995. A mean of the surface charge parameters describing H+ binding accounted for more than 95% of the variable charge on the soils. For individual soils, the NICA model gave a fit to the experimental data with mean R2 values for Ca, Cd, Cu, Pb and Zn of 1.00, 0.906, 0.879 (two concentrations only), 0.825 and 0.918 respectively. When mean adsorption parameters, instead of values determined for each soil individually, are used, the model gave mean R2s for Ca, Cd, Cu, Pb and Zn of 0.938, 0.941, 0.998 (two concentrations only), 0.978 and 0.935. It seems that the NICA model can be used to describe the surface charge and adsorption of cations by whole soils. The mean adsorption parameters appear to describe the adsorption behavior of the soil nearly as well as the individually fitted parameters. This implies that mean parameters for these agricultural soils may provide satisfactory predictions for the adsorption behavior of similar soils. Key words: NICA model, NICCA, surface charge, cation binding, agricultural soil

Developments in quantitative soil resource assessment (Pedometrics '98)

Geoderma ◽  
2000 ◽  
Vol 97 (3-4) ◽  
pp. 147 ◽  
Author(s):  
Mary Collins ◽  
Alex McBratney ◽  
Marc Voltz ◽  
Christian Walter
Keyword(s):  
Resource Assessment ◽  
Soil Resource ◽  
Soil Resource Assessment

scholarly journals Geo-Spatial Analysis of Population Density and Annual Income to Identify Large-Scale Socio-Demographic Disparities

2021 ◽  
Vol 10 (7) ◽  
pp. 432
Author(s):  
Nicolai Moos ◽  
Carsten Juergens ◽  
Andreas P. Redecker
Keyword(s):  
Population Density ◽  
Large Scale ◽  
Methodological Approach ◽  
Spatial Relationship ◽  
Postal Code ◽  
Annual Income ◽  
Choropleth Maps ◽  
Clustering Approach ◽  
Relationship Of ◽  
Insight Into

This paper describes a methodological approach that is able to analyse socio-demographic and -economic data in large-scale spatial detail. Based on the two variables, population density and annual income, one investigates the spatial relationship of these variables to identify locations of imbalance or disparities assisted by bivariate choropleth maps. The aim is to gain a deeper insight into spatial components of socioeconomic nexuses, such as the relationships between the two variables, especially for high-resolution spatial units. The used methodology is able to assist political decision-making, target group advertising in the field of geo-marketing and for the site searches of new shop locations, as well as further socioeconomic research and urban planning. The developed methodology was tested in a national case study in Germany and is easily transferrable to other countries with comparable datasets. The analysis was carried out utilising data about population density and average annual income linked to spatially referenced polygons of postal codes. These were disaggregated initially via a readapted three-class dasymetric mapping approach and allocated to large-scale city block polygons. Univariate and bivariate choropleth maps generated from the resulting datasets were then used to identify and compare spatial economic disparities for a study area in North Rhine-Westphalia (NRW), Germany. Subsequently, based on these variables, a multivariate clustering approach was conducted for a demonstration area in Dortmund. In the result, it was obvious that the spatially disaggregated data allow more detailed insight into spatial patterns of socioeconomic attributes than the coarser data related to postal code polygons.

scholarly journals Potentiating Effect of Mandelate and Lactate on Chemically Induced Germination in Members of Bacillus cereus Sensu Lato

2017 ◽  
Vol 83 (24) ◽  
Author(s):  
Alistair H. Bishop
Keyword(s):  
Bacillus Cereus ◽  
Large Scale ◽  
Germination Rate ◽  
Dependent Manner ◽  
Clostridium Sporogenes ◽  
Specific Chemical ◽  
Content Type ◽  
Ph Range ◽  
Significant Discovery ◽  
The Impact

ABSTRACT Endospores of the genus Bacillus can be triggered to germinate by a limited number of chemicals. Mandelate had powerful additive effects on the levels and rates of germination produced in non-heat-shocked spores of Bacillus anthracis strain Sterne, Bacillus cereus, and Bacillus thuringiensis when combined with l-alanine and inosine. Mandelate had no germinant effect on its own but was active with these germinants in a dose-dependent manner at concentrations higher than 0.5 mM. The maximum rate and extent of germination were produced in B. anthracis by 100 mM l-alanine with 10 mM inosine; this was equaled by just 25% of these germinants when supplemented with 10 mM mandelate. Half the maximal germination rate was produced by 40% of the optimum germinant concentrations or 15% of them when supplemented with 0.8 mM mandelate. Germination rates in B. thuringiensis were highest around neutrality, but the potentiating effect of mandelate was maintained over a wider pH range than was germination with l-alanine and inosine alone. For all species, lactate also promoted germination in the presence of l-alanine and inosine; this was further increased by mandelate. Ammonium ions also enhanced l-alanine- and inosine-induced germination but only when mandelate was present. In spite of the structural similarities, mandelate did not compete with phenylalanine as a germinant. Mandelate appeared to bind to spores while enhancing germination. There was no effect when mandelate was used in conjunction with nonnutrient germinants. No effect was produced with spores of Bacillus subtilis, Clostridium sporogenes, or C. difficile. IMPORTANCE The number of chemicals that can induce germination in the species related to Bacillus cereus has been defined for many years, and they conform to specific chemical types. Although not a germinant itself, mandelate has a structure that is different from these germination-active compounds, and its addition to this list represents a significant discovery in the fundamental biology of spore germination. This novel activity may also have important applied relevance given the impact of spores of B. cereus in foodborne disease and B. anthracis as a threat agent. The destruction of spores of B. anthracis, for example, particularly over large outdoor areas, poses significant scientific and logistical problems. The addition of mandelate and lactate to the established mixtures of l-alanine and inosine would decrease the amount of the established germinants required and increase the speed and level of germination achieved. The large-scale application of “germinate to decontaminate” strategy may thus become more practicable.

scholarly journals Metachronal waves in magnetic micro-robotic paddles for artificial cilia

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Matthew T. Bryan ◽  
Elizabeth L. Martin ◽  
Aleksandra Pac ◽  
Andrew D. Gilbert ◽  
Feodor Y. Ogrin
Keyword(s):  
Large Scale ◽  
Point Of Care ◽  
Hydrodynamic Response ◽  
Flow Speeds ◽  
Break Time ◽  
Large Scale Manufacture ◽  
Fresh Insight ◽  
Metachronal Waves ◽  
Insight Into ◽  
Phase Differences

AbstractBiological cilia generate fluid movement within viscosity-dominated environments using beating motions that break time-reversal symmetry. This creates a metachronal wave, which enhances flow efficiency. Artificially mimicking this behaviour could improve microfluidic point-of-care devices, since viscosity-dominated fluid dynamics impede fluid flow and mixing of reagents, limiting potential for multiplexing diagnostic tests. However, current biomimicry schemes require either variation in the hydrodynamic response across a cilia array or a complex magnetic anisotropy configuration to synchronise the actuation sequence with the driving field. Here, we show that simple modifications to the structural design introduce phase differences between individual actuators, leading to the spontaneous formation of metachronal waves. This generates flow speeds of up to 16 μm/s as far as 675 μm above the actuator plane. By introducing metachronal waves through lithographic structuring, large scale manufacture becomes feasible. Additionally, by demonstrating that metachronal waves emerge from non-uniformity in internal structural mechanics, we offer fresh insight into the mechanics of cilia coordination.

scholarly journals Address of the President Sir Henry Dale, C.B.E., at the Anniversary Meeting, 1 December 1941

1942 ◽  
Vol 179 (978) ◽  
pp. 233-260 ◽  
Keyword(s):  
Technical College ◽  
High Speed ◽  
Large Scale ◽  
Electrical Engineering ◽  
The United States ◽  
The Past ◽  
Pure Mathematics ◽  
Symbolic Structure ◽  
The Church ◽  
Insight Into

This is the first occasion on which I have had the great honour of addressing the Royal Society on this anniversary of its foundation. According to custom, I begin with brief mention of those whom death has taken from our Fellowship during the past year, and whose memories we honour. Alfred Young (1873-1940), distinguished for his contributions to pure mathematics, was half brother to another of our Fellows, Sydney Young, a chemist of eminence. Alfred Young had an insight into the symbolic structure and manipulation of algebra, which gave him a special place among his mathematical contemporaries. After a successful career at Cambridge he entered the Church, and passed his later years in the country rectory of Birdbrook, Essex. His devotion to mathematics continued, however, throughout his life, and he published a steady stream of work in the branch of algebra which he had invented, and named ‘quantitative substitutional analysis’. He lived to see his methods adopted by Weyl in his quantum mechanics and spectroscopy. He was elected to our Fellowship in 1934. With the death of Miles Walker (1868-1941) the Society loses a pioneer in large-scale electrical engineering. Walker was a man of wide interests. He was trained first for the law, and even followed its practice for a period. Later he studied electrical engineering under Sylvanus Thompson at the Finsbury Technical College and became his assistant for several years. Thereafter, encouraged by Thompson, he entered St John’s College, Cambridge, with a scholarship, and graduated with 1st Class Honours in both the Natural Sciences and the Engineering Tripos. Having entered the service of the British Westinghouse Company, he was sent by them to the United States of America to study electrical engineering with the parent company in Pittsburgh. On his return to England he became their leading designer of high-speed electrical generators

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